The present invention relates in general to semiconductor devices and, more particularly, to integrated circuits formed with inductive components such as planar inductors and transformers.
Many semiconductor devices integrate both active and passive components on the same die in order to reduce the manufacturing cost of electronic systems. For example, many wireless communication systems are fabricated with an integrated circuit that includes a low noise radio frequency input amplifier and a bandpass or impedance matching filter formed on the same semiconductor die. The filter often includes a planar inductor or transformer which is integrated on the semiconductor die along with the amplifier's active transistors.
However, most integrated electromagnetic devices such as inductors suffer from a low quality factor owing to a low resistivity semiconductor substrate used to avoid a latchup condition of the integrated circuit. The proximity of the inductor to the low resistivity substrate induces parasitic image currents in the substrate that load the inductor and reduce its quality factor. Moreover, the semiconductor material used to form the substrate typically has a high dielectric constant which produces a high parasitic capacitance of the inductor, which reduces its frequency response and degrades the performance of the integrated circuit.
Hence, there is a need for an integrated circuit and method of fabrication that provides a high quality factor inductive component in order to maintain a low system cost and a high performance of the integrated circuit.